I just ran my codes again today...about a week ago I ran them and it said Bank #1 was running lean...the code I just pulled told me that Bank #2 is running lean now and says nothing about Bank #1. What could cause one side to read lean one day and then the other the next? Is that a symptom of a bad fuel pump. I tested the fuel pressure and got 31psi and at WOT got 37psi...I am really confused on how to fix this since it seems like my fuel pump is working ok due to the fuel pressure...I don't know if it could be an intake leak or something like that since the lean condition changed sides...I am just really confused on how to fix this...any other suggestions on what I should check or what specific problem this might be?